Pros: Fire power; reliability, multi-fuel capability, large fuel capacity; strong-built
Cons: heavy, tricky to prime, soft flame susceptible to wind
Optimus phased out 111 Hiker (in blue paint), and replaced it with 111C Hiker (in black case), which is supposed to be an improved version. The picture you see on 111 is actually that of 111C. There are variants of 111 Hiker: 111 (kerosene), 111B (white gas only) and 111T (Triple Fuel).
111 Hiker has a silent burner, while 111B has a roarer burner. Its roar is a bit on the loud side, and one needs to raise the voice somewhat, in order to converse normally over a roaring 111B. Although the silent burner produces a larger flame than the roarer burner, the former is more susceptible to wind compared to the latter, and a windshield is recommended. It will help priming and operating the stove efficiently.
When I first had the used 111, I did not know how it worked. In order to burn kerosene or white gas, one needs to take out the restrictor. A restrictor is a short metal pipe with either two or three holes at one end. One needs to have a restrictor (three holes, PN5213) and the proper jet or nipple (whatever you are fond of calling it) installed in the burner, however, in order to burn denatured alcohol in it. Although the factory instruction says one needs to use the restrictor when using gasoline, I think it is a misprint: do not use the restrictor, when using white gas or kerosene. At least my particular stove cannot produce a blue flame while burning white gas with a restrictor in the burner. It also has trouble with kerosene, for it can only produce a sooty orange flame, even with the restrictor uninstalled. 2 bad (I suspect I need to install a jet with smaller orifice).
Besides these quirks, how does 111 perform? Admirably. Because the silent burner of 111 has a lot of metal in it, it takes a moderate amount of priming fuel to get it up to the priming temperature. The burner is of a moderately complicated design, and it needs to be primed with an ample amount of alcohol, in order to achieve the blue flame at the first shot (especially with 111B).
First remove the brass burner skirt and fill the priming dish 2/3 with alcohol. Replace the brass skirt. Light the primer dish. While the burner is being primed, pump a few strokes to pressurize the fuel tank. Sometimes, when the user opens the valve, the flame begins to burn under the caps, and it makes the noise similar to what you hear, when combustion takes place inside the expansion chamber of Colemans green briefcase stove. When this happens, you cannot see the flame outside 111's burner cap, and the cap will glow: immediately shut off the valve, or your burner might melt a little.
For this reason, I prefer to light the burner after the priming flame died out, or almost died. If you open the valve when the burner is not at the proper temperature, the blue flame will float above the burner. If the valve is turned up more, the flame will either burst into orange fireball or just go out, giving off nasty but explosive fuel vapor. So don't be stingy on alcohol, or try to save a match.
If you run out of alcohol to prime it, you can take a medicine dropper full of fuel from the tank and prime it. Petroleum based priming is a lot more effective than alcohol, but with white gas, be careful: its volatility can surprise you unpleasantly.
After you have achieved the blue flame and pumped hard, you should be able to see strong, needle-like flames shooting out of the small holes radially around the outer cap. If this does not happen, it means that the stove is losing air pressure, and you need to look at the following:
1) Check the fuel cap. It has one large rubber washer and one small, hidden check gasket. Both tend to become brittle over time and use. Either replace with what you fashion, or buy a new cap from A & H guys in Tustin, CA. They are the only authorized parts/ service center in the US. The Cheaper way is to go to a local harware store, and get a few O rings with a 3/4 inch outside diameter (An assorted pack would give you the option of many different sizes). The thicker the better. Or, you can get a rubber washer from plumbing section, with a 3/4 inch O.D. Nitrile rubber is impervious to pertoleum product, but the washer may or may not come in nitrile rubber. Get a few, and bring home and dip one in the white gas for a few hours, and see how it maintains its strength and integrity. As long as it does not increase it size too much, and stays soft, it is usable. Once you locate the kind you want, they are pretty cheaper than getting a whole new cap, so get a few, and replace as needed.
2) Open the fuel pump cap, and remove the pump rod, and inspect the rubber O-ring. Replace it as needed, clean the inside of the pump tube, or add lubricating oil. By using the multi key (the pipe with the black plastic knob), reach into the pump tube, and mate the end into the check valve inside: this keeps the fuel and air inside the fuel tank and from entering the pump tube as you pump up. Remove it carefully, and examine it, and replace as needed. Reinstall it with care, so as not to cross thread it. Do not tighten too much, or you will strip the thread: this will ruin your day and render the fuel tank unusable. Replace the whole pump rod assembly. The stove should have the airtight seal now.
Turning the 111's valve all the way to right should shut off; turning all the way to the left cleans the jet; the max. flame is the middle position. If your 111 doe not function this way, the cleaning needle needs to be synchronized with the spindle. When you remove the jet and cleaning needle to clean out carbon deposits, you need to take the following steps to put it back together:
1) Drain the fuel from the tank and store it in a safe container; relieve the air pressure from the fuel tank. Warning: Do not EVER look down the fuel jet and open the valve, when the tank is pressurized. It will spit hot fuel into your eyes, and you won't see much afterwards. Remove the outer and inner burner caps, and look down into the tube. You will see the fuel jet. Remove it carefully with the multi tool.
2) Now open the fuel valve (counter-clockwise) with the multi tool, and you will see the built-in cleaning needle rise up out of the hole. Pick it out gently, and set it aside. Close the valve all the way, and gently stick the needle into the rubber eraser of a pencil. Take care not to bend it. Drop in the needle with the teeth-side facing the fuel tank. Now turn the multi key counter-clockwise, counting the number of teeth the spindle misses on the cleaning needle. At count four, turn clockwise all the way, remove the pencil, and then reinstall the jet, reinstall the inner and outer caps. Now the spindle is synchronized with the cleaning needle.
111 Hiker puts out an impressive amount of heat, and it boils 1 liter of water under 4 minutes, when pumped up hard. While 111's flame control is sensitive for simmering and cooking eggs, 111B's roarer burner will scorch some food even at the lower setting. Any lower, it may produce yellow flame or die out.
111's high power is particularly suited for a large group, but it comes with a price. 111 Hiker is a rather heavy stove: 54 oz empty. With max fuel (2-hr. burn time), it adds up to 71 oz. Yet it is half the weight of Coleman's two-burner green briefcase. If this is too heavy, ask your girlfriend to talk a guy into carrying it for you, or hire a sherpa.
The steel case of Optimus 111 is a lot stronger than the Coleman's. It is fit for an extended expedition. You won't be cold or hungry with Optimus 111.